To pursue the research objectives of the Membrane Biology Section, viz. the investigation of the location of specific molecules and the dynamics of their distribution within the cell, we concentrated our research in three main areas: localization of oncogenes and oncogene products, dynamic distribution of laminin receptors, and ultrastructural investigation of specific ligands in protozoan parasites. To this end, we continued our previous efforts to reach and provide ultrastructural and cytochemical support to intramural and contract laboratories at the NIH. The work of Dr. Shen Rulong is especially noteworthy since it continues and expands his virtually unique efforts in the immunogold localization of oncogenes and their products. This work is now extended to studies involving the participation of the v-Mos oncogene in programmed cell death (apoptosis). We have also continued our collaboration with investigators at the Laboratory of Parasitic Diseases: Dr. Paulo Pimenta applied many of the methods learned as a visiting fellow in our section to continue his work on intracellular parasites (Bonania ostrae, B. edulis and Leishmania major). Support of his research over the past years has made it possible for Dr. Pimenta to become a leader in the molecular cytochemistry of surface molecules with relevance in the infective processes by protozoan parasites responsible for tropical diseases, a problem of increasing and alarming relevance in the US. Our work resulted in the publication of seven papers and two invited reviews.